It is well known to provide a hard wearing surface by applying a pavement to it. The pavement may be formed from a wide variety of materials such as asphalt or concrete but a particularly attractive solution to providing a paved area is the use of paving elements. These elements are laid side-by-side to cover the required area and may be of different shapes or colours to provide an aesthetically pleasing finished surface. The elements are formed as individual units of relatively small size and may be formed with shapes that interlock with one another to inhibit relative movement once laid. Typically, the paving elements will be made from a concrete moulded to the desired shape and finish.
It is usual to manufacture the paving elements as clusters that can be formed in a single mould. The clusters can then be stacked on a palette or other transport device, one layer upon another and transported to the site for installation. With some arrangements, mechanical devices are used to transfer clusters from the palette and lay them directly upon the surface to be paved. The next cluster is then laid side-by-side and rapid installation of the paving is accomplished.
One problem found with the manufactured installation of clusters is that the periphery of the cluster is delimited by a common joint line. That common joint line may allow relative movement between the adjacent clusters even though the individual elements in the cluster are inhibited from relative movement.
One solution to the above problem has been to provide a specially shaped cornerstone for each cluster that attempts to lock the two clusters to one another. However, this arrangement is difficult to install and mould and complicates the stacking of clusters one above the other.
Even though the stones within each cluster are formed with interlocking configurations, it is frequently possible for stones to move relative to one another along a pair of mutually perpendicular axes. Such relative movement may occur en masse to give a diagonal shift within the cluster of stones.
Some configurations of stone provide indents that inhibits movement along one of the axes but still permits separation along the other axis, thereby again permitting a separation between two parts of the cluster. In practice, it is found that even highly complex shapes permit a degree of separation or sliding along particular axes when arranged in a repeating pattern in a cluster.
One solution that has been proposed is to interlock each stone with a through recess and a corresponding projection that extends between the upper and lower faces of the element. Typically, the projection is formed as a dovetail. However, such an arrangement is relatively difficult to manufacture and introduces a line of weakness at the pin of the dovetail on the block. It has also been proposed to use a key element between the stones but then the keys are visible.
It is therefore an object of the present invention to obviate or mitigate the above disadvantages.